Long-distance cable



BEST AVAILABLE com Nov. 2 '1 926'."

/lyl AnoRNEv Patented Nov. 2, 1926.

As Iregards thelonstructionofthe longdistance' cables, it has :beenffproposed to replace thel ,multiplertwin y formation by the spiral, qua'df ,formation i. el', .an arrangement in:whichithe fourf'conductors of ahquad are all ,twistcd'to'gether simultaneously. In the latter :casey owing to the comparatively high sidetofsidejc'apacity pf the spiral -quad ormation the phantom circuits cannot be uti- 40.v lizedoISpeakinglpurposes tothe sa'me eX- tent asthefphantom circuits of multi-ple# twin cahles'g',v (for, 'well-known reasons the quads cannotfbef used for :telephonie purposes).; IThey:phantom telephone circuits' can, however, readily ybe dispensed with inasmuch as, in the same cross-sectional area,'

a Vspiral quad cable can accommodate approxmately more pairs of conductors,

than a multipley twin cable. :There results 50 therefore vin both systems practically the 355i AV'LABLE COPY atlon ojridfric#y I' conductors again g Itv 'vfsted to'- ERLINfGERMANrfAssIGNoR .To AMERICAN TELEPHONE AND i QTELEGRAPH coiarANmAcoRronArIoN oElN'EW YORK y ma; presa vantageso'f economical and' f an, opercording' to this 'inyention ,utilizing I Aneref.v ly` fthe' side? "circuits-,fiori telephonie vfp'urp o ses, While reservingf the' phantom connections torsignaling.fandy telegraphy. ItV is y thus hantom 79+ possible to accommodate in each circuit ahigh-grade telegraph dup ex con-4 nection 'or several signaling connections, or if desired bothtelegraph and signaling connections; together, without thetelephonieintercoursel in the speaking 'connections 75;, beingunfavorably influenced Thel several kinds of connections, are held apartuin'this y arrangement bythe range of the frequencies used in veach'case@ While directfvcurrentg. high speed telegraphy in the majority of '50 l cases only requires ,frequencies up to 'T5-100l v cycles, the signaling connections operated by 'alternating current are voperated with frequencies up to about 200 cycles. The speaking frequenciespro'pen which range S5 above 300 cycles, are not used asa rule according to this invention.

It is 4further limportant to note that the transmission of the ,frequencies Which are used for telegraphic and signaling Vpurposes is possible over sufficiently long distances in spiralquad circuits without coil-loading or continuous loading. The absence of loading, apart from the saving of costs, entails the further advantage that the telegraphs inserted in the phantom connections may easily be worked duplex.

If a cable in multiple-twin formation with n-side'circuits, and therefore n-l-n/Qr-Bn/Q channels, is compared with a spirally twistedV In this arrangement it is possible to forin each telegraphloop from two physical circuits fas Wellas from two phantom circuits.

`All'fsuch circuits'v will never v'be entirely symmetrical and balancing of discontinu.-

it-iesfrequires considerable expenditure, Ac-

cording' to this invention the mutual absence of disturbance between' the telegraph' loop'andits two component circuits is ob# tained Without balancing the cable, `by deriv'inof` the" current 4im' ulses .used for telef graph and' signaling A'purposes of the harmonics falling within the range of the-speaking frequencies.

effectedby inserting in series' with the tele'- Hgraphic equipment a filter having a range of '"transmission.up toabout 15G-250 cycles. A

filterofthis kind will further act towards barring 'the"wayjthroug h the telegraphic equipment fto :all audio-frequent imbalance currents as may arise from the unavoidable laclrof symmetry orf the cable, whereby a v ery 'materialsource of disturbances is done away'lwith. By' further inserting filters which do not transmit sub-audio frequencies HVinthe telephoniev equipments whereby telegraph" currents `are prevented, from entering into the latter, lthus "insuring a complete mutual absence of disturbance.

It ,is further important that the mutual protectionfjof the side circuits on the one hand and the phantom circuit on the other hand does not .require any balancing of the differences in capacity at the loading points nor any other balancing mea-ns to .be distributed-over the whole cable line. According to this invention mutual absence of disturbance is solely obtained by the use of filters in the terminal or repeating station equipments. Obviously the simplification thus obtained is very remarkable.

The most perfect embodiment of this invention, as far as the technical means` are concerned, is obtained if two inter-twisted pairs of conductors are available for the formation of a telegraph loop, for instance two related side circuits of a coil-loaded cable in spiral quad formation. In this case each quad offers two normal speaking connections and a telegraphic connection fit for duplexing. The means employed in the side circuits for increasing inductivity are not This may "for instance be assi AvAiLABLE copy subjected to maenetization by the current owing in the telegraph loop, so that there is no danger of the loading coils or the iron whipping getting polarized or the telephone transmission impaired byv flutter effec-ts,

In the drawings afixed to this specification and forming'part thereof two diagrams of connections embodying my invention are ,shown.by.'way.ofexanipley v.

fEach' modiicatiioninomprises a long distance cablevwith quadded conductors 1, 2, and 3, 'tare the: conductors of the quad which contains the `side circuits the -speaking equipments and't','connectedaslusuaL19 and 10 .are two .dferenbial repeating coils., tothe centre 'taps 'the leLdS- [ai `'diipl'eir telegraph =Sfet12 areconnected.' y A lowpass filter 11; Serves reif-'choking 9am-'he higher j hannonicsi .ig-

second, ofthtelegraphic impulses.

Operate Witholitl' any Iinutile l '1'.` frequencies; The speaking "equipment 5, and i 6 an'd'thetelegraphic equipmentzlgwill then even' in" case, that the "side-teerde; capacities have not bee'nbalancedl ,In Fig. 2, 1, Zand 3, '4 are again thetvvo side V'olllits fofth 1 quad, iand the Speaking equiieets 'Pitetected against sub-audio frequencies byhighcentre' tapjd'ierential coils 4"fo-r. 'telegrapny 13' isa filter transmittingonly frequenciesupf' to A c cles-and in Which'the current im-j" pulses o the 'telegraph Vset 14' operatedwith direct current are dep'rivedfoftlieirffhigherj harmonics.' 15 is a band 'filter having ali transmission v range betwveen and 150 cycles. 16' and 17 are twojalternating cur-A rent telegraph instruments fsets'fwhi'ch are' operated on the Morse' plan, use'beingmade of electricor other selective'ineans'. for the working frequencies and 140 C. P. M.

and which forinstan'ce form connections between the telephone operators' of the toll' circuits 1, 2 and 3, 4: in 'order to prepare the long-distance calls.

Repeater equipments' are 'dispensed with in the side circuits by insert-ing differential coils in the ends ofeachtwocircuits which r shall be interconnected, and by further indesire to be limited to lthe exact details'o'f" eEsT AvAlLABLE coPY means and connections shown and described, for obvious modifications will occur to a person skilled in the art.

The method of increasing the economy of cables, which consists in arranging the conductors of the cable in spiral quad formation groupedto give two side circuits and 'range only, and side circuits for the trans mission of telephone currents.

In testimony whereof I aix my signature OTTO SATTELBERG. 

